What If My New Knee Becomes Infected?

Signs of knee infection may include fever, fatigue, swelling, redness, localized warmth, drainage of fluid from the knee, or a recurrence of pain or stiffness after full post-operative recovery has been achieved. An x-ray or bone scan can also help your surgeon determine if there is an infection.

If there is visible fluid coming from the surgical site or incision, your surgeon may recommend a culture. A sample of the fluid is collected and tested in a lab to determine what bacteria are present. Blood tests and needle aspiration of fluid surrounding the joint may also be needed to definitively diagnose an infection (Parvizi, et al., 2018).

Non-Surgical Treatment
Surgical Treatments

If it has only been a few weeks since your knee replacement, you may be a candidate for D.A.I.R. This involves surgical debridement (cleaning/washing, removing infected tissue) of the infected knee, followed by 6 weeks of IV antibiotics. You can expect periodic blood tests, needle aspirations, or cultures to determine if the antibiotics are working.

• Only about 50% of patients experience an eradication of infection (Vasso & Panni, 2014).

• This method involves debridement, removal of the infected prosthesis, and implantation of the new prosthesis in one surgery.
  • Benefits
    • Fewer surgeries
    • Less expensive
    • Less risk for potential complications from having multiple surgeries
    • Potential for a shorter hospital stay and reduced rehabilitation time
    • Lower reinfection rates (4.3% vs. 13.5% in two-stage revisions)
  • Outcomes
    • 80-90% of patients experience eradication of infection (Kildow, et al. 2020).

This treatment option has been used for patients with infections that may have been present for months or years. Eradicating an infection can be difficult if the infection has been present for a long time. It is more common to undergo a two-stage (compared to a one-stage) revision for infection in the United States as it is generally believed to work better.

Stage 1: Stage one involves debridement, removal of the infected knee, and placing an antibiotic-loaded spacer in the joint. The spacer is a device that is implanted in the knee after the infected prosthetic is removed. The spacer allows for joint stability and mobility as well as an infusion of antibiotics into the infected joint (Mazzucchelli, et al. 2015). Stage one also involves 6 weeks or more of IV antibiotics. You will have periodic blood tests to determine if the antibiotics are working.

Stage 2: After it is determined the infection is clear, stage two involves removing the antibiotic spacer, debriding the joint, and implanting a new prosthesis.

• Benefits
  • Two chances to debride tissues
  • Two chances to assess response to antibiotics during the interval between surgeries
• Outcomes and Risks (Negus, et al., 2017)
  • More risk associated with two major surgeries
  • Potential for spacer failure leading to further surgeries
  • More expensive
  • Two separate recovery and rehabilitation periods
  • 10% of patients become unfit for the second stage of surgery (Gomez, et al., 2015)
  • Increased chance of reinfection 93% (Haddad, et al., 2014)

There are many different types of knee spacers to treat infected total knee replacements.

Static Spacers

• For severe bone loss, a static spacer is used. This spacer prevents motion at the knee and acts as a fusion. Many surgeons perform this procedure by placing cement within your knee replacement
• Dr. Morton uses an internal rod to provide stability to your knee during this phase. This provides additional stability, preventing your spacer from dislodging during your recovery.

Mobile Spacers

• Mobile spacers are made of cement that’s bonded to the ends of your femur (thigh bone) and tibia (shin bone). Newer techniques are performed using mobile implants made of metal and polyethylene (plastic) components that are surrounded by antibiotic-impregnated cement. These spacers allow for a more functional knee during your temporary spacer phase. Some patients with these spacers find their knee replacement functional enough that they do need a second surgery to their knee.

Infection following a knee replacement is uncommon but can be a serious complication. Contact your surgeon immediately if you experience fever, fatigue, swelling, redness, localized warmth on the knee, drainage of fluids from the knee, or a recurrence of pain or stiffness after a full post-operative recovery has been achieved. With appropriate treatment, curing an infection is possible with an expectation of a full recovery and return to normal activities and mobility.